Magmatic rifting in the Main Ethiopian Rift began in thick continental lithosphere; the case of the Galema Range

Stratigraphy and eruptive history of Gedemsa caldera volcano, Central Main Ethiopian Rift

“…Previously, geophysical studies in the region (e.g in Boset, Northern MER) revealed the presence of crustal melt zones and seismicity, suggesting ongoing magmatic processes influencing the tectonic activity (Whaler and Hautot, 2006;Keir et al, 2009a;Bastow et al, 2010). In congruence with the geophysical studies, recent data from field and petrological investigations indicate that the intrusions in the MER are assisting the rift evolution by creating a mechanically weak crustal lithosphere (Nicotra et al, 2021;Chiasera et al, 2021;Oliveira et al, 2022;Wong et al, 2023). Similarly, evidence of repeated volcanic eruptions within the MER show that the onset and evolution of the MER have been heavily facilitated by the presence of melts within the crust.…”

Subsurface structure of magmatic segments during continental breakup: Perspectives from a gravity data analysis along the Main Ethiopian Rift

“…The gravity maximum over the MER floor and the sudden increase in the gravity anomalies (>−210 mGa l) after the northern termination of the Gedemsa magmatic segment (Figure 3) are attributed to the cumulative response of the addition of magmatic underplated intrusions and northward crustal thinning (Tiberi et al, 2005;Mickus et al, 2007). The gravity maxima over rift margin volcanic zones (SDZFZ, YVTZ, and Galema range) are interpreted to be magmatic intrusions into the crust in the form of dike swarms (Chiasera et al, 2021). The gravity maxima over the magmatic segments and the rift margin volcanic zones on the rift flanks occur at a crustal level (~< 30 km), based on the high pass Frontiers in Earth Science frontiersin.org filtered gravity anomaly map (Figure 4), suggesting a concentrated or focused magmatic activity in these regions.…”

“…From embryonic continental rifting in the south to incipient oceanic spreading in the north, the MER encompasses many phases of rift sector evolution (e.g., Hayward and Ebinger, 1996;Corti, 2009;Ebinger et al, 2017;Chiasera et al, 2021). Based on the onset of rifting and the age of volcanism (Corti, 2009;Corti et al, 2020), the MER has commonly been divided into three sectors: Southern Main Ethiopian Rift (SMER), Central Main Ethiopian Rift (CMER) and Northern Main Ethiopian Rift (NMER) (Figure 1).…”